I cry unhappily during record — Sondheim? (8)
I believe the answer is:
lyricist
'sondheim?' is the definition.
(I know this)
'i cry unhappily during record' is the wordplay.
'unhappily' indicates anagramming the letters.
'during' indicates putting letters inside.
'record' becomes 'list' (list is a type of record).
'i'+'cry'='icry'
'icry' with letters rearranged gives 'yric'.
'yric' put within 'list' is 'LYRICIST'.
(Other definitions for lyricist that I've seen before include "Writer of words for songs" , "Ira Gershwin, perhaps" , "The one who writes the words for songs" , "Book writer" , "Writer of words, as opposed to music" .)